Volt free thermostat?

Hi I was trying to install my wireless thermostat on my combi boiler, it' a single channel receiver, its different to what I had on my old boiler, can any body help as I don' understand what wire runs from the block cn5 to the receiver , then from the receiver to the male connector,
many thanks in advance.

The two wires labelled "Room Thermostat 24V. Note use contacts free of voltage" that are presently connected to your existing thermostat, go to the the Hive receiver terminals 1 and 3. it doesn't matter which way around they go, it is just a switch.

The Hive receiver also needs a 230V supply connecting to the Neutral and Live terminals N & L to provide it with power. This supply to the receiver should be connected to the same mains supply as the boiler, and fed from the same fused supply. The Hive doesn't need an earth, so park it in the 'earth tether'

If your boiler has an integral timeswitch i.e. time control wasn't provided by your original thermostat, then it should be set to be permanently 'on' otherwise it will interfere with the Hive.

I don' understand what wire runs from the block cn5 to the receiver , then from the receiver to the male connector,

Click to expand...

I can't say anything about the above unfortunately, because I can't see your photo clearly enough and you don't say what make / model it is. However you should now be able to work it out for yourself from my comments earlier.

The main characteristic of a volt-free contact in this context, is that it is fully floating - not referred to earth or any supply voltage, AC or DC.
They are usually derived from relay contacts or similar, and can be N/O, N/C or C/O. In this case the thermostat may switch these either by bi-metal strip or similar mechanical system, or via a thermistor controlled electronic circuit driving a relay coil.
The opposite of a volt-free contact, is where the output of semiconductor device switches the load directly, with no isolation and the device electrode voltages are present on the 'contacts' and may effect the switched equipment. If the semiconductor device is a transistor, the output (contacts) may be described as "Common Emitter", "Common Collector", "Common Source", "Common Drain", "Open Collector", "Open Emitter", or similar.
Solid-state relays are now becoming more common, in which they incorporate voltaic (or galvanic) isolation - usually via an opto-isolator - these can also represent an electrically-floating set of relay contacts.